Process of treating ores.



- NI ED STATES PATENT OFFICE.

LOUIS M. :PRITOHARD, or BOISE, IDAHO.

PROCESS OF TREATING ORES.

Specification of Letters Patent.

Patented July so, 1' 907.

Application filed June 26, 1906, Serial No. 323,521-

pectors in the field for testing ores are not well adapted to thetesting" of ores generally, but more especially base and low grade ores.To ascertain the value of his samples it is usually necessary for theprospector to send them to an assayer, who is often located at a distantpoint, and to have a reliable report numerous assays are required. Thismethod is not only costly but requires considerable time in sending thesamples and waiting for thereturns. I

The present invention has for its object the provision of a processwhereby the prospector himself can make the tests of'his ores for goldin the field, make as many as he desires, and do so atvery great savingof expense and time; and also by means of which he can arrive at a'fair,approximation of the gold .valueof his. ores.

The process is only adapted to the testing and reduction of auriferousores and will be described as so ap- It is 'well known that the elementsof the halogen group are solventsof gold, and of these, iodin is themost stable, has the least affinity for hydrogen, dissolves fewersubstancesother than gold, and isleast liable to .injuriously affectthose who handle it. In the present invention it is proposed to takeadvantage of the properties of iodin in a process-for treatingauriferous ores, particularly for assaying purposes. Iodin mixed with 1potassium iodid can be easily carried by the pr0spector asa part of'hisoutfit as dry salts, to which he can add water to make the solventsolution when he desires 'tion of iodin to dissolve the gold and addingmercury to the solution to form an amalgam and then separating the goldfrom the mercury.

In carrying out the process the] ore. is ground very fine and screenedto remove. the Eoars'er particles.

Previous to grinding most ores. can be roasted to advantag e, thusfreeing the ore of most of the interfering elements, makingit moreporous,-so that the gold is more I easily leachedbut; some ores however,such a'sthose cuntaining galena; can be better treated withoutthe Ipreliminaryroasting. The pulverized ore' is treated red color of thesolution disappears.

with an excess of a solution of iodin dissolved in potassium iodid in anaqueous solution. The solution is added until the mixture retains a darkred color. While the ore is being acted on by the solvent the grindingcan be continued at intervals to remove any slimes or precipitates thatmay coat the particles'and thereby permit the solution to act directlyupon the gold particles. After the ore has been acted upon for asuflicient length of time, depending upon the quantity. and

- fineness of the gold in the ore, the solution is separated from thepulp. To obtain all of'the solution it may be washed from the pulp withwater. After the solution has been separated from the pulp, mercury isadded and the mixture is vigorously agitated until all of the Ifsufiicient mercury has been added, and it is better that it shouldbe toomuch rather than too little, the liquid gradually clears and the mercuryflours and sometimes turps black, when all of the gold will be foundamalgamated with the mercury. The mercury reduces the gold in solutionto the metallic state and immediately forms an amalgam with it. Theexcess of iodin andpotassium iodid in the solution, aidsgreatly in thuscollecting the gold by its action upon the mercury principally bycausing it to break up and flour during the agitation, thusexposingavery large surface of the mercury to act upon the'gold insolution, causing its amalgamation very quickly. The amalgam is thenwashed to free it from the solution and other extraneous matter. Finallythe gold andmercury are separated by distillation or by treating theamalgam with nitric acid to dissolve out the mercury and otherimpurities if any. It is preferable to dissolve with nitric acid for thereason that it leaves the gold in a pure state, and when smallquantities are taken it willbe in the shape of a small gold button,inconvenient form to be measured 'or weighed.

While the process has been particularly described as being adapted tothe use of the prospector, .yet it can be used on a large scale for thecommercial reduc-'' tion of ore. I

Having thus described my'invention, what I claim and desire to secure byLetters-Patent is, a,

1. The process of treating ores consisting in dissolving" the gold inthe ore in a solution of iodin, adding mercury to the solution to forman amalgam, and separating theamalgam into its componentparts. 1 2. Theprocess of treating auriiferous ores consisting in pulverizing the ore,tree-ting it with iodin dissolved in an aqueous solution of potassiumiodid to dissolve the gold, agitating the solution thus Iforrnedwithmercury to form an amalgam with the gold, and separating the gold fromthe mercury.

In'testimonywhereof I- have "hereunto aflixed my slgna turejnthepresencemf two witnesses. 1 F LOUIS Mi PRITCHARD.

witnesses:

ALFRED ihrnrnnu, K

CHABLEsL. LiNGnNr-ufirnn.

